Collagen is the most important protein in the cranial-maxillofacial area and in the matrix stabilization as well as its structure-function relationship is vital in order to understand its mode of support. Collagen is involved in the resorption of bone in periodontitis, regeneration in wound healing in oral surgery and the repair of all tissues. Among one of the most important extracellular post-translational modifications of collagen is its crosslinking which is initiated by lysyl oxidase. The preparation of substrates for assaying lysyl oxidase is tedious and laborious and yields a substrate of limited specific activity so that it so that its overall usefulness is restricted. The method proposed here for the preparation of a collagen substrate for lysyl oxidase is simple and straightforward and is capable of yielding a substrate that is almost unlimited in its potential. Using very high specific activity [3H]NaBH4, one fantamole of collagen could possibly contain 40,000 DPM of tritium. The substrate preparation is much less expensive than others that are in existence.